Polyolefins such as high density polyethylene (HDPE) homopolymer and linear low density polyethylene (LLDPE) copolymer can be produced using various combinations of catalyst systems and polymerization processes. Ziegler-Natta and chromium-based catalyst systems can, for example, produce ethylene polymers having good extrusion processability and polymer melt strength and bubble stability in blown film applications, typically due to their broad molecular weight distribution (MWD). Metallocene based catalyst systems can, for example, produce ethylene polymer having good impact strength, tear resistance, and optical properties, but often at the expense of poor extrusion processability, melt strength, and bubble stability.
In some end-uses, such as blown film applications, it can be beneficial to have the properties of a metallocene-catalyzed LLDPE copolymer, but with improved processability, shear thinning, melt strength, and bubble stability. Accordingly, it is to these ends that the present invention is generally directed.